In refrigeration apparatuses such as air-conditioning apparatuses, there is often a difference between the optimal refrigerant quantity for an air-cooling operation and the optimal refrigerant quantity for an air-warming operation, and there is also often a difference between the capacity of a heat source-side heat exchanger functioning as a heat radiator of refrigerant during the air-cooling operation and the capacity of a usage-side heat exchanger functioning as a heat radiator of refrigerant during the air-warming operation. In a conventional refrigeration apparatus, the capacity of the heat source-side heat exchanger is often greater than the capacity of the usage-side heat exchanger, and refrigerant that cannot be accommodated by the usage-side heat exchanger during the air-warming operation is temporarily stored in an accumulator or the like.
Recently there are small high-performance heat exchangers such as the one presented in Japanese Laid-open Patent Application No. 6-143991.